Cahills

Mayflies

Caddisflies

Stoneflies

Scientific Names

Match	Scientific Name
	Stenacron
	Stenacron interpunctatum
	Maccaffertium ithaca

Like most common names, "Cahill" can refer to more than one taxon. They're previewed below, along with 6 specimens. For more detail click through to the scientific names.

Mayfly Genus Stenacron

These are sometimes called Cahills.

The species in this genus were formerly classified in Stenonema. See the genus Maccaffertium for details. Only one species, Stenacron interpunctatum, is important to fly fishermen. See its page for details.

Stenacron interpunctatum (Light Cahill) Mayfly Nymph

View 7 Pictures

Collected June 5, 2005 from in
Added to Troutnut.com by on May 25, 2006

Male Stenacron (Light Cahills) Mayfly Dun

View 13 Pictures

Collected May 27, 2005 from in
Added to Troutnut.com by on May 22, 2006

Male Stenacron interpunctatum (Light Cahill) Mayfly Spinner

View 8 Pictures

Collected June 10, 2005 from in
Added to Troutnut.com by on May 26, 2006

See 5 more specimens...

Mayfly Species Stenacron interpunctatum

These are very rarely called Cahills.

This is the best of the sporadic summer hatches known to anglers as Light Cahills. It was formerly known as Stenonema canadense and is considered by most angling historians as the model for that classic Catskill pattern.

Stenacron interpunctatum (Light Cahill) Mayfly Nymph

View 7 Pictures

Collected June 5, 2005 from in
Added to Troutnut.com by on May 25, 2006

Female Stenacron interpunctatum (Light Cahill) Mayfly Dun

View 6 PicturesThis is a fairly small late-season female Stenacron dun.

Collected August 22, 2006 from in
Added to Troutnut.com by on August 23, 2006

Male Stenacron interpunctatum (Light Cahill) Mayfly Spinner

View 8 Pictures

Collected June 10, 2005 from in
Added to Troutnut.com by on May 26, 2006

Mayfly Species Maccaffertium ithaca

These are very rarely called Cahills.

Maccaffertium ithaca (Light Cahill) Mayfly Nymph

View 9 PicturesThis specimen seems to be of the same species as a dun I photographed which emerged from another nymph in the same sample.

Collected May 29, 2007 from in
Added to Troutnut.com by on June 4, 2007

Female Maccaffertium ithaca (Light Cahill) Mayfly Dun

View 10 PicturesThis female looks very much like a male I collected a few hundred miles away a few days later, so I'm guessing it's the same species, which I believe is Maccaffertium mediopunctatum.

Collected May 23, 2007 from in
Added to Troutnut.com by on June 4, 2007

See 2 more specimens...

Jargon Defined:

Dun: Mayflies have two adult stages. They first emerge from the water as duns (scientifically known as the subimago stage). They then molt into the spinner (imago) stage, in which they mate and die. Sometimes the word "dun" is confusingly used to refer to a brownish gray color in fly tying materials.

Nymph: The juvenile, underwater stages of mayflies, stoneflies, dragonflies, and damselflies and other aquatic insects whose juvenile stages are covered by hard exoskeletons. The word can also refer to the fishing flies which imitate these creatures, in which case it is used as a blanket term for flies imitating any underwater stage of an invertebrate (except for crayfish and leeches).